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Ruby 中的私有模块方法

发布于 2024-07-10 02:02:08 字数 743 浏览 10 评论 0原文

我有一个由两部分组成的问题

最佳实践

  • 我有一种算法，可以使用公共接口对数据结构执行一些操作
  • 它目前是一个具有许多静态方法的模块，除了一个公共接口之外，所有静态方法都是私有的方法。
  • 有一个实例变量需要在所有方法之间共享。

这些是我能看到的选项，哪个是最好的？：

  • Module 带有静态（ruby 中的“module”）方法
  • Class 带有静态方法
  • Mixin > 用于包含到数据结构中的模块
  • 重构修改该数据结构的算法部分（非常小），并使其成为调用算法模块的静态方法的混合

技术部分

有没有办法制作私有模块方法？

module Thing
  def self.pub; puts "Public method"; end
  private
  def self.priv; puts "Private method"; end
end

其中的private似乎没有任何效果，我仍然可以毫无问题地调用Thing.priv。

原文

I have a two part question

Best-Practice

  • I have an algorithm that performs some operation on a data structure using the public interface
  • It is currently a module with numerous static methods, all private except for the one public interface method.
  • There is one instance variable that needs to be shared among all the methods.

These are the options I can see, which is the best?:

  • Module with static ('module' in ruby) methods
  • Class with static methods
  • Mixin module for inclusion into the data structure
  • Refactor out the part of the algorithm that modifies that data structure (very small) and make that a mixin that calls the static methods of the algorithm module

Technical part

Is there any way to make a private Module method?

module Thing
  def self.pub; puts "Public method"; end
  private
  def self.priv; puts "Private method"; end
end

The private in there doesn't seem to have any effect, I can still call Thing.priv without issue.

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评论（10）

凡尘雨 2024-07-17 02:02:08

我认为最好的方法（主要是现有库的编写方式）是在模块内创建一个处理所有逻辑的类，并且该模块只是提供了一种方便的方法，例如

module GTranslate
  class Translator
    def perform(text)
      translate(text)
    end

    private

    def translate(text)
      # do some private stuff here
    end
  end

  def self.translate(text)
    t = Translator.new
    t.perform(text)
  end
end

I think the best way (and mostly how existing libs are written) to do this is by creating a class within the module that deals with all the logic, and the module just provides a convenient method, e.g.

module GTranslate
  class Translator
    def perform(text)
      translate(text)
    end

    private

    def translate(text)
      # do some private stuff here
    end
  end

  def self.translate(text)
    t = Translator.new
    t.perform(text)
  end
end
回复 原文
若能看破又如何 2024-07-17 02:02:08

还有 Module.private_class_method，它可以说表达了更多意图。

module Foo
  def self.included(base)
    base.instance_eval do
      def method_name
        # ...
      end
      private_class_method :method_name
    end
  end
end

对于问题中的代码：

module Thing
  def self.pub; puts "Public method"; end
  def self.priv; puts "Private method"; end
  private_class_method :priv
end

Ruby 2.1 或更高版本：

module Thing
  def self.pub; puts "Public method"; end
  private_class_method def self.priv; puts "Private method"; end
end

There's also Module.private_class_method, which arguably expresses more intent.

module Foo
  def self.included(base)
    base.instance_eval do
      def method_name
        # ...
      end
      private_class_method :method_name
    end
  end
end

For the code in the question:

module Thing
  def self.pub; puts "Public method"; end
  def self.priv; puts "Private method"; end
  private_class_method :priv
end

Ruby 2.1 or newer:

module Thing
  def self.pub; puts "Public method"; end
  private_class_method def self.priv; puts "Private method"; end
end
回复 原文
安稳善良 2024-07-17 02:02:08

将方法作为 lambda 存储在类变量/常量中怎么样？

module MyModule
  @@my_secret_method = lambda {
    # ...
  }
  # ...
end

用于测试：
UPD：6年后此代码的巨大更新显示了声明私有方法的更清晰的方式d

module A
  @@L = lambda{ "@@L" }
  def self.a ; @@L[] ; end
  def self.b ; a ; end

  class << self
    def c ; @@L[] ; end
    private
    def d ; @@L[] ; end
  end
  def self.e ; c ; end
  def self.f ; self.c ; end
  def self.g ; d ; end
  def self.h ; self.d ; end

  private
  def self.i ; @@L[] ; end
  class << self
    def j ; @@L[] ; end
  end

  public
  def self.k ; i ; end
  def self.l ; self.i ; end
  def self.m ; j ; end
  def self.n ; self.j ; end
end

for expr in %w{ A.a A.b A.c A.d A.e A.f A.g A.h A.i A.j A.k A.l A.m A.n }
  puts "#{expr} => #{begin ; eval expr ; rescue => e ; e ; end}"
end

在这里我们看到：

A.a => @@L
A.b => @@L
A.c => @@L
A.d => private method `d' called for A:Module
A.e => @@L
A.f => @@L
A.g => @@L
A.h => private method `d' called for A:Module
A.i => @@L
A.j => @@L
A.k => @@L
A.l => @@L
A.m => @@L
A.n => @@L

1）@@L可以不能从外部访问，但几乎可以从任何地方访问
2) 类 << 自己 ; 私人的 ; def 成功地使方法 d 无法通过 self. 从外部和内部访问，但如果没有它，则无法访问 - 这很奇怪
3) 私有; self. 和 private ； 类<< self 不要将方法设为私有——无论有没有 self. 都可以访问它们。

What's about storing methods as lambdas within class variables/constants?

module MyModule
  @@my_secret_method = lambda {
    # ...
  }
  # ...
end

For test:
UPD: huge update of this code after 6 years shows cleaner way to declare private method d

module A
  @@L = lambda{ "@@L" }
  def self.a ; @@L[] ; end
  def self.b ; a ; end

  class << self
    def c ; @@L[] ; end
    private
    def d ; @@L[] ; end
  end
  def self.e ; c ; end
  def self.f ; self.c ; end
  def self.g ; d ; end
  def self.h ; self.d ; end

  private
  def self.i ; @@L[] ; end
  class << self
    def j ; @@L[] ; end
  end

  public
  def self.k ; i ; end
  def self.l ; self.i ; end
  def self.m ; j ; end
  def self.n ; self.j ; end
end

for expr in %w{ A.a A.b A.c A.d A.e A.f A.g A.h A.i A.j A.k A.l A.m A.n }
  puts "#{expr} => #{begin ; eval expr ; rescue => e ; e ; end}"
end

Here we see that:

A.a => @@L
A.b => @@L
A.c => @@L
A.d => private method `d' called for A:Module
A.e => @@L
A.f => @@L
A.g => @@L
A.h => private method `d' called for A:Module
A.i => @@L
A.j => @@L
A.k => @@L
A.l => @@L
A.m => @@L
A.n => @@L

1) @@L can not be accesses from outside but is accessible from almost everywhere
2) class << self ; private ; def successfully makes the method d inaccessible from outside and from inside with self. but not without it -- this is weird
3) private ; self. and private ; class << self do not make methods private -- they are accessible both with and without self.

回复 原文
忆离笙 2024-07-17 02:02:08

创建私有模块或类

常量永远不是私有的。 但是，可以创建模块或类而不将其分配给常量。

因此 :private_class_method 的替代方法是创建一个私有模块或类并在其上定义公共方法。

module PublicModule
  def self.do_stuff(input)
    @private_implementation.do_stuff(input)
  end

  @private_implementation = Module.new do
    def self.do_stuff(input)
      input.upcase # or call other methods on module
    end
  end
end

用法：

PublicModule.do_stuff("whatever") # => "WHATEVER"

请参阅 Module.new 和 Class.new。

Make a private module or class

Constants are never private. However, it's possible to create a module or class without assigning it to a constant.

So an alternative to :private_class_method is to create a private module or class and define public methods on it.

module PublicModule
  def self.do_stuff(input)
    @private_implementation.do_stuff(input)
  end

  @private_implementation = Module.new do
    def self.do_stuff(input)
      input.upcase # or call other methods on module
    end
  end
end

Usage:

PublicModule.do_stuff("whatever") # => "WHATEVER"

See the docs for Module.new and Class.new.

回复 原文
手心的温暖 2024-07-17 02:02:08

是如何在单个模块中嵌套多个类的解决方案，并且能够通过使用 extend 调用可从任何嵌套类访问的模块上的私有方法：

module SomeModule

  class ClassThatDoesNotExtendTheModule
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  class ClassThatDoesExtendTheModule
    extend SomeModule
  
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  class AnotherClassThatDoesExtendTheModule
    extend SomeModule
  
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  private

  def private_class_on_module
    puts 'some private class was called'
  end
  
end

以下 输出显示正在运行的解决方案：

> SomeModule::ClassThatDoesNotExtendTheModule.random_class_method

NameError: undefined local variable or method `private_class_on_module' for SomeModule::ClassThatDoesNotExtendTheModule:Class


> SomeModule::ClassThatDoesExtendTheModule.random_class_method

some private class was called


> SomeModule::ClassThatDoesExtendTheModule.private_class_on_module

NoMethodError: private method `private_class_on_module' called for SomeModule::ClassThatDoesExtendTheModule:Class


> SomeModule::AnotherClassThatDoesExtendTheModule.random_class_method

some private class was called


> SomeModule::AnotherClassThatDoesExtendTheModule.random_class_method

NoMethodError: private method `private_class_on_module' called for SomeModule::AnotherClassThatDoesExtendTheModule:Class

Here's a solution for how you can have multiple classes nested within a single module, with the ability to call a private method on the module that's accessible from any of the nested classes, by making use of extend:

module SomeModule

  class ClassThatDoesNotExtendTheModule
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  class ClassThatDoesExtendTheModule
    extend SomeModule
  
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  class AnotherClassThatDoesExtendTheModule
    extend SomeModule
  
    class << self
      def random_class_method
        private_class_on_module
      end
    end
  end

  private

  def private_class_on_module
    puts 'some private class was called'
  end
  
end

Some output to show the solution in action:

> SomeModule::ClassThatDoesNotExtendTheModule.random_class_method

NameError: undefined local variable or method `private_class_on_module' for SomeModule::ClassThatDoesNotExtendTheModule:Class


> SomeModule::ClassThatDoesExtendTheModule.random_class_method

some private class was called


> SomeModule::ClassThatDoesExtendTheModule.private_class_on_module

NoMethodError: private method `private_class_on_module' called for SomeModule::ClassThatDoesExtendTheModule:Class


> SomeModule::AnotherClassThatDoesExtendTheModule.random_class_method

some private class was called


> SomeModule::AnotherClassThatDoesExtendTheModule.random_class_method

NoMethodError: private method `private_class_on_module' called for SomeModule::AnotherClassThatDoesExtendTheModule:Class
回复 原文
一刻暧昧 2024-07-17 02:02:08
module Writer
  class << self
    def output(s)
      puts upcase(s)
    end

    private

    def upcase(s)
      s.upcase
    end
  end
end

Writer.output "Hello World"
# -> HELLO WORLD

Writer.upcase "Hello World"
# -> so.rb:16:in `<main>': private method `upcase' called for Writer:Module (NoMethodError)

module Writer
  class << self
    def output(s)
      puts upcase(s)
    end

    private

    def upcase(s)
      s.upcase
    end
  end
end

Writer.output "Hello World"
# -> HELLO WORLD

Writer.upcase "Hello World"
# -> so.rb:16:in `<main>': private method `upcase' called for Writer:Module (NoMethodError)
回复 原文
任性一次 2024-07-17 02:02:08

当模块混合时，您可以使用“包含”方法来做一些奇特的事情。我认为这符合您的要求：

module Foo
  def self.included(base)
    class << base 
      def public_method
        puts "public method"
      end
      def call_private
        private_method
      end
      private
      def private_method
        puts "private"
      end
    end
  end
end

class Bar
  include Foo
end

Bar.public_method

begin
  Bar.private_method
rescue
  puts "couldn't call private method"
end

Bar.call_private

You can use the "included" method to do fancy things when a module is mixed in. This does about what you want I think:

module Foo
  def self.included(base)
    class << base 
      def public_method
        puts "public method"
      end
      def call_private
        private_method
      end
      private
      def private_method
        puts "private"
      end
    end
  end
end

class Bar
  include Foo
end

Bar.public_method

begin
  Bar.private_method
rescue
  puts "couldn't call private method"
end

Bar.call_private
回复 原文
作业与我同在 2024-07-17 02:02:08

不幸的是，private 仅适用于实例方法。 在类中获取私有“静态”方法的一般方法是执行以下操作：

class << self
  private

  def foo()
   ....
  end
end

诚然，我还没有在模块中这样做过。

Unfortunately, private only applies to instance methods. The general way to get private "static" methods in a class is to do something like:

class << self
  private

  def foo()
   ....
  end
end

Admittedly I haven't played with doing this in modules.

回复 原文
早茶月光 2024-07-17 02:02:08

除非您通过方法参数显式传递数据，否则此方法不允许与私有方法共享数据。

module Thing
  extend self

  def pub
    puts priv(123)
  end

  private
  
  def priv(value)
    puts "Private method with value #{value}"
  end
end

Thing.pub
# "Private method with value 123"

Thing.priv
# NoMethodError (private method `priv' called for Thing:Module)

This method won't allow sharing data with the private methods unless you explicitly pass the data by method parameters.

module Thing
  extend self

  def pub
    puts priv(123)
  end

  private
  
  def priv(value)
    puts "Private method with value #{value}"
  end
end

Thing.pub
# "Private method with value 123"

Thing.priv
# NoMethodError (private method `priv' called for Thing:Module)
回复 原文
被翻牌 2024-07-17 02:02:08

一个好的方法是这样的

module MyModule
  class << self
    def public_method
      # you may call the private method here
      tmp = private_method
      :public
    end

    private def private_method
      :private
    end
  end
end

# calling from outside the module
puts MyModule::public_method

A nice way is like this

module MyModule
  class << self
    def public_method
      # you may call the private method here
      tmp = private_method
      :public
    end

    private def private_method
      :private
    end
  end
end

# calling from outside the module
puts MyModule::public_method
回复 原文
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